Time to first defibrillation and survival outcomes of out-of-hospital cardiac arrest with refractory ventricular fibrillation

Knowledge and barriers of out of hospital cardiac arrest bystander intervention and public access automated external defibrillator use in the Northeast of England: a cross-sectional survey study

Intervention by members of the public during an out of hospital cardiac arrest (OHAC) including resuscitation attempts and accessible automated external defibrillator (AED) has been shown to improve survival. This study aimed to investigate the OHCA and AED knowledge and confidence, and barriers to intervention, of the public of North East England, UK. This study used a face-to-face cross-sectional survey on a public high street in Newcastle, UK. Participants were asked unprompted to explain what they would do when faced with an OHCA collapse. Chi-Square analysis was used to test the association of the independent variables sex and first aid trained on the participants' responses. Of the 421 participants recruited to our study, 82.9% (n = 349) reported that they would know what to do during an OHCA collapse. The most frequent OHCA action mentioned was call 999 (64.1%, n = 270/421) and 58.2% (n = 245/421) of participants reported that they would commence CPR. However, only 14.3% (n = 60/421) of participants spontaneously mentioned that they would locate an AED, while only 4.5% (n = 19/421) recounted that they would apply the AED. Just over half of participants (50.8%, n = 214/421) were first aid trained, with statistically more females (57.3%, n = 126/220) than males (43.9%,  n = 87/198) being first aiders (p = 0.01 χ2 = 7.41). Most participants (80.3%, n = 338/421) knew what an AED was, and 34.7% (n = 326/421) reported that they knew how to use one, however, only 11.9% (n = 50/421) mentioned that they would actually shock a patient. Being first aid trained increased the likelihood of freely recounting actions for OHCA and AED intervention. The most common barrier to helping during an OHCA was lack of knowledge (29.9%, n = 126/421). Although most participants reported they would know what to do during an OHCA and had knowledge of an AED, low numbers of participants spontaneously mentioned specific OHCA and AED actions. Improving public knowledge would help improve the public's confidence of intervening during an OHCA and may improve OHCA survival.

Ventricular fibrillation waveform properties influenced by thoracic impedance guided chest compressions in a porcine model

BACKGROUND AND OBJECTIVE

Quantitative measures extracted from ventricular fibrillation (VF) waveform reflect the metabolic state of the myocardium and are associated with survival outcome. The quality of delivered chest compressions during cardiopulmonary resuscitation are also linked with survival. The aim of this research is to explore the viability and effectiveness of a thoracic impedance (TI) based chest compression (CC) guidance system to control CC depth within individual subjects and influence VF waveform properties.

METHODS

This porcine investigation includes an analysis of two protocols. CC were delivered in 2 min episodes at a constant rate of 110 CC min-1. Subject-specific CC depth was controlled using a TI-thresholding system where CC were performed according to the amplitude (ZRMS, 0.125 to 1.250 Ω) of a band-passed TI signal (ZCC). Protocol A was a retrospective analysis of a 12-porcine study to characterise the response of two VF waveform metrics: amplitude spectrum area (AMSA) and mean slope (MS), to varying CC quality. Protocol B was a prospective 12-porcine study to determine if changes in VF waveform metrics, due to CC quality, were associated with defibrillation outcome.

RESULTS

Protocol A: A directly proportional relationship was observed between ZRMS and CC depth applied within each subject (r = 0.90; p <0.001). A positive relationship was observed between ZRMS and both AMSA (p <0.001) and MS (p <0.001), where greater TI thresholds were associated with greater waveform metrics.

PROTOCOL B

MS was associated with return of circulation following defibrillation (odds ratio = 2.657; p = 0.043).

CONCLUSION

TI-thresholding was an effective way to control CC depth within-subjects. Compressions applied according to higher TI thresholds evoked an increase in AMSA and MS. The response in MS due to deeper CC resulted in a greater incidence of ROSC compared to shallow chest compressions.

Surgical mask-to-mouth ventilation as an alternative ventilation technique during CPR: A crossover randomized controlled trial

INTRODUCTION

Chest compression with rescue breathing improves outcomes in cardiac arrest. However, the efficacy of rescue breathing through surgical masks has not been investigated.

OBJECTIVE

We aimed to compare the tidal volume generated by mouth-to-mouth ventilation (MMV) with that generated by surgical mask-to-mouth ventilation (SMV), mouth-to-surgical mask ventilation (MSV), and surgical mask-to-surgical mask ventilation (SSV) in a manikin.

METHODS

A crossover randomized controlled trial was conducted in 42 medical personnel volunteers randomly assigned to perform four ventilation techniques: MMV (no protective equipment), SMV (participant wearing a mask), MSV (manikin wearing a mask), and SSV, (both participant and manikin wearing a mask). The average tidal volume and the proportion of adequate ventilation, evaluated using a manikin, were compared across different ventilation methods.

RESULTS

The average tidal volume of MMV (828 ± 278 ml) was significantly higher than those of the MSV (648 ± 250 ml, P < 0.001) and SSV (466 ± 301 ml, P < 0.001), but not SMV (744 ± 288 ml, P = 0.054). Adequate ventilation was achieved in 144/168 (85.7%) cases in the MMV group, a proportion significantly higher than in the SMV (77.4%, P = 0.02), MSV (66.7%, P < 0.001) and SSV (39.3%, P < 0.001) groups. The willingness to perform SMV was higher than that to perform MMV.

CONCLUSIONS

MMV resulted in a superior average tidal volume when compared to both MSV and SSV. However, SMV achieved a comparable average tidal volume to MMV.

Development of an automatic device performing chest compression and external defibrillation: An animal-based pilot study

BACKGROUND

Automatic chest compression devices (ACCDs) can promote high-quality cardiopulmonary resuscitation (CPR) and are widely used worldwide. Early application of automated external defibrillators (AEDs) along with high-quality CPR is crucial for favorable outcomes in patients with cardiac arrest. Here, we developed an automated CPR (A-CPR) apparatus that combines ACCD and AED and evaluated its performance in a pilot animal-based study.

METHODS

Eleven pigs (n = 5, A-CPR group; n = 6, ACCD CPR and AED [conventional CPR (C-CPR)] group) were enrolled in this study. After 2 min observation without any treatment following ventricular fibrillation induction, CPR with a 30:2 compression/ventilation ratio was performed for 6 min, mimicking basic life support (BLS). A-CPR or C-CPR was applied immediately after BLS, and resuscitation including chest compression and defibrillation, was performed following a voice prompt from the A-CPR device or AED. Hemodynamic parameters, including aortic pressure, right atrial pressure, coronary perfusion pressure, carotid blood flow, and end-tidal carbon dioxide, were monitored during resuscitation. Time variables, including time to start rhythm analysis, time to charge, time to defibrillate, and time to subsequent chest compression, were also measured.

RESULTS

There were no differences in baseline characteristics, except for arterial carbon dioxide pressure (39 in A-CPR vs. 33 in C-CPR, p = 0.034), between the two groups. There were no differences in hemodynamic parameters between the groups. However, time to charge (28.9 ± 5.6 s, A-CPR group; 47.2 ± 12.4 s, C-CPR group), time to defibrillate (29.1 ± 7.2 s, A-CPR group; 50.5 ± 12.3 s, C-CPR group), and time to subsequent chest compression (32.4 ± 6.3 s, A-CPR group; 56.3 ± 10.7 s, C-CPR group) were shorter in the A-CPR group than in the C-CPR group (p = 0.015, 0.034 and 0.02 respectively).

CONCLUSIONS

A-CPR can provide effective chest compressions and defibrillation, thereby shortening the time required for defibrillation.

Improved immune algorithm for sudden cardiac death first aid drones site selection

AIMS

Out-of-hospital cardiac arrest (OHCA) requires a fast emergency response, while traditional emergency takes too long to meet the demand. Combining a drone with a defibrillator can provide rapid resuscitation of OHCA patients. The aims are to improve survival in OHCA and to minimize the total system cost.

METHODS

We developed an integer planning model for sudden cardiac death (SCD) first aid drone siting based on a set covering model with the stability of the siting system as the main constraint, considering the rescue time and total system cost. Using 300 points to simulate potential cardiac arrest locations in the main municipal district of Tianjin, China, the SCD first aid drone siting points are solved using an improved immune algorithm.

RESULTS

Based on the actual parameters set by the SCD first aid drone, 25 siting points were solved in the main municipal district of Tianjin, China. These 25 sites were able to cover 300 simulated potential demand points. The average rescue time was 127.18 s and the maximum rescue time was 296.99 s. The total system cost was 136,824.46 Yuan. Comparing the pre- and post-algorithm solutions, the system stability was improved by 42.22%, and the maximum number of siting points corresponding to demand points was reduced by 29.41% and the minimum number was increased by 16.86%, which is closer to the average.

CONCLUSIONS

We propose the SCD emergency system and use the improved immune algorithm for example solving. Comparing the solution results using the pre- and post-improvement algorithms, the cost solved by the post-improvement algorithm is less and the system is more stable.

Impact of Number of Defibrillation Attempts on Neurologically Favourable Survival Rate in Patients with Out-of-Hospital Cardiac Arrest

AIM

of the study: Defibrillation plays a crucial role in early return of spontaneous circulation (ROSC) and survival of patients with out-of-hospital cardiac arrest (OHCA) and shockable rhythm. Prehospital adrenaline administration increases the probability of prehospital ROSC. However, little is known about the relationship between number of prehospital defibrillation attempts and neurologically favourable survival in patients treated with and without adrenaline.

METHODS

Using a nationwide Japanese OHCA registry database from 2006 to 2020, 1,802,084 patients with OHCA were retrospectively analysed, among whom 81,056 with witnessed OHCA and initial shockable rhythm were included. The relationship between the number of defibrillation attempts before hospital admission and neurologically favourable survival rate (cerebral performance category score of 1 or 2) at 1 month was evaluated with subgroup analysis for patients treated with and without adrenaline.

RESULTS

At 1 month, 18,080 (22.3%) patients had a cerebral performance category score of 1 or 2. In the study population, the probability of prehospital ROSC and favourable neurological survival rate were inversely associated with number of defibrillation attempts. Similar trends were observed in patients treated without adrenaline, whereas a greater number of defibrillation attempts was counterintuitively associated with favourable neurological survival rate in patients treated with prehospital adrenaline.

CONCLUSIONS

Overall, a greater number of prehospital defibrillation attempts was associated with lower neurologically favourable survival at 1 month in patients with OHCA and shockable rhythm. However, an increasing number of shocks (up to the 4th shock) was associated with better neurological outcomes when considering only patients treated with adrenaline.

Predefibrillation end-tidal CO2 and defibrillation success in out-of-hospital cardiac arrest: an observational cohort study

BACKGROUND

Predefibrillation end-tidal CO₂ (ETCO₂) may predict defibrillation success and could guide defibrillation timing in ventricular fibrillation (VF) cardiac arrest. This relationship has only been studied using advanced airways. Our aim was to evaluate this relationship using both basic (bag-valve-mask (BVM)) and advanced airways (supraglottic airways and endotracheal tubes).

METHODS

Prehospital patient records and defibrillator files were abstracted for patients with out-of-hospital cardiac arrest in Ontario, Canada, with initial VF cardiac rhythms between 1 January 2018, and 31 December 2019. Analyses assessed the relationship between each predefibrillation ETCO₂ reading and defibrillation outcomes at the subsequent 2 min pulse check (ie, VF, asystole, pulseless electrical activity (PEA) or return of spontaneous circulation (ROSC)), accounting for airway types used during resuscitation. Multivariable logistic regression evaluated the association between the first documented predefibrillation ETCO₂ and postshock VF termination or ROSC.

RESULTS

Of 269 cases abstracted, 153 had predefibrillation ETCO₂ measurements and were included in the study. Among these cases, 904 shocks were delivered and 44.4% (n=401) had predefibrillation ETCO₂ measured. The first ETCO₂ reading was more often from BVM (n=134) than advanced airways (n=19). ETCO₂ readings were lower when measured through BVM versus advanced airways (30.5 mm Hg (4.06 kPa) (±14.4 mm Hg (1.92 kPa)) vs 42.1 mm Hg (5.61 kPa) (±22.5 mm Hg (3.00 kPa)), _adjANOVA p<0.01). Of all shocks with ETCO₂ reading (n=401), no difference in preshock ETCO₂ was found for subsequent shocks that resulted in persistent VF (32.2 mm Hg (4.29 kPa) (±15.8 mm Hg (2.11 kPa))), PEA (32.8 mm Hg (4.37 kPa) (±17.1 mm Hg (2.30 kPa))), asystole (32.4 mm Hg (4.32 kPa) (±20.6 mm Hg (2.75 kPa))) or ROSC (32.5 mm Hg (4.33 kPa) (±15.3 mm Hg (2.04 kPa))), analysis of variance p=0.99. In the multivariate analysis using the initial predefibrillation ETCO₂, there was no association with VF termination on the subsequent shock (adjusted OR (_adjOR) 0.99, 95% CI 0.97 to 1.02, p=0.57) or ROSC (_adjOR 1.00, 95% CI 0.97 to 1.03, p=0.94) when evaluated as a continuous or categorical variable.

CONCLUSION

Predefibrillation ETCO₂ measurement is not associated with VF termination or ROSC when basic and advanced airways are included in the analysis. The role of predefibrillation ETCO₂ requires careful consideration of the type of airway used during resuscitation.

The number and level of first-contact emergency medical services crew and clinical outcomes in out-of-hospital cardiac arrest with dual dispatch response

OBJECTIVE

This study aimed to evaluate the association between the number and level of emergency medical technicians (EMTs) in the first-contact emergency medical services (EMS) unit and the clinical outcomes of out-of-hospital cardiac arrest (OHCA) with a dual dispatch response.

METHODS

Adult nontraumatic EMS-treated OHCAs between 2015 and 2018 in a nationwide database, were enrolled. The main exposure was the number and certification level of first-contact EMS crew: three versus two members, proportion of EMT intermediate level (EMT-I) over 50% versus under or equal to 50%. Good neurologic recovery was selected as the primary outcome. Multilevel multivariable logistic regression analysis was conducted to calculate adjusted odds ratios and confidence intervals.

RESULTS

A total of 26,867 patients were enrolled and analyzed. Good neurologic recovery was different across the study groups: 5.4% in the two-member crews, 7.2% in the three-member crews, 5.9% in the low EMT-I proportion crews, and 6.8% in the high EMT-I proportion crews. In the main analysis, statistically significant differences for favorable outcomes were found between the three-member and two-member crews, and the high EMT-I proportion and low EMT-I proportion crews; for good neurologic recovery, adjusted odds ratios (95% confidence interval) were 1.23 (1.06-1.43) for three-member crews, and 1.28 (1.17-1.40) for a high EMT-I proportion.

CONCLUSION

The higher number and level of first-contact EMS crew was associated with better neurologic recovery in adult nontraumatic OHCA with a dual-dispatched EMS response.

Cardiac arrest: An interdisciplinary scoping review of clinical literature from 2020

Objectives

The Interdisciplinary Cardiac Arrest Research Review (ICARE) group was formed in 2018 to conduct an annual search of peer-reviewed literature relevant to cardiac arrest. Now in its third year, the goals of the review are to highlight annual updates in the interdisciplinary world of clinical cardiac arrest research with a focus on clinically relevant and impactful clinical and population-level studies from 2020.

Methods

A search of PubMed using keywords related to clinical research in cardiac arrest was conducted. Titles and abstracts were screened for relevance and sorted into 7 categories: Epidemiology & Public Health Initiatives; Prehospital Resuscitation, Technology & Care; In-Hospital Resuscitation & Post-Arrest Care; Prognostication & Outcomes; Pediatrics; Interdisciplinary Guidelines & Reviews; and a new section dedicated to the coronavirus disease 2019 (COVID-19) pandemic. Screened manuscripts underwent standardized scoring of methodological quality and impact on the respective fields by reviewer teams lead by a subject matter expert editor. Articles scoring higher than 99 percentiles by category were selected for full critique. Systematic differences between editors' and reviewers' scores were assessed using Wilcoxon signed-rank test.

Results

A total of 3594 articles were identified on initial search; of these, 1026 were scored after screening for relevance and deduplication, and 51 underwent full critique. The leading category was Prehospital Resuscitation, Technology & Care representing 35% (18/51) of fully reviewed articles. Four COVID-19 related articles were included for formal review that was attributed to a relative lack of high-quality data concerning cardiac arrest and COVID-19 specifically by the end of the 2020 calendar year. No significant differences between editor and reviewer scoring were found among review articles (P = 0.697). Among original research articles, section editors scored a median 1 point (interquartile range, 0-3; P < 0.01) less than reviewers.

Conclusions

Several clinically relevant studies have added to the evidence base for the management of cardiac arrest patients including methods for prognostication of neurologic outcome following arrest, airway management strategy, timing of coronary intervention, and methods to improve expeditious performance of key components of resuscitation such as chest compressions in adults and children.

Are there disparities in the location of automated external defibrillators in England?

Background

Early defibrillation is an essential element of the chain of survival for out-of-hospital cardiac arrest (OHCA). Public access defibrillation (PAD) programmes aim to place automated external defibrillators (AED) in areas with high OHCA incidence, but there is sometimes a mismatch between AED density and OHCA incidence.

Objectives

This study aimed to assess whether there were any disparities in the characteristics of areas that have an AED and those that do not in England.

Methods

Details of the location of AEDs registered with English Ambulance Services were obtained from individual services or internet sources. Neighbourhood characteristics of lower layer super output areas (LSOA) were obtained from the Office for National Statistics. Comparisons were made between LSOAs with and without a registered AED.

Results

AEDs were statistically more likely to be in LSOAs with a lower residential but higher workplace population density, with people predominantly from a white ethnic background and working in higher socio-economically classified occupations (p < 0.05). There was a significant correlation between AED coverage and the LSOA Index of Multiple Deprivation (IMD) (r = 0.79, p = 0.007), with only 27.4% in the lowest IMD decile compared to about 45% in highest. AED density varied significantly across the country from 0.82/km² in the north east to 2.97/km² in London.

Conclusions

In England, AEDs were disproportionately placed in more affluent areas, with a lower residential population density. This contrasts with locations where OHCAs have previously occurred. Future PAD programmes should give preference to areas of higher deprivation and be tailored to the local community.

Time to amiodarone administration and survival outcomes in refractory ventricular fibrillation

OBJECTIVE

International guidelines recommend amiodarone for out-of-hospital cardiac arrest (OHCA) in refractory ventricular fibrillation (VF). While early appropriate interventions have been shown to improve OHCA survival, the association between time to amiodarone and survival remains to be established.

METHODS

Included were adult OHCA in refractory VF, between January 2015 and December 2019, who received a resuscitation attempt with amiodarone from Queensland Ambulance Service paramedics. Patient characteristics and survival outcomes were described. Factors associated with survival were investigated, with a focus on time from arrest to amiodarone administration. Optimal time window for amiodarone administration was determined, and factors influencing whether amiodarone was given within the optimal time window were examined.

RESULTS

A total of 502 patients were included. The average (range) time from arrest to amiodarone was 25 (4-83) min. Time to amiodarone was negatively associated with survival (adjusted odds ratio 0.93 for event survival; 95% confidence interval 0.89-0.97). The optimal time window for amiodarone was within 23 min following arrest. Patients receiving amiodarone within the optimal time had significantly better survival than those receiving it outside this window (event survival 38.3% vs 20.6%, P < 0.001; discharge survival 25.5% vs 9.7%, P < 0.001; 30-day survival 25.1% vs 9.7%, P < 0.001). Paramedic response time (adjusted odds ratio 0.96; 95% confidence interval 0.92-0.99) and time from arrest to intravenous access (0.71; 0.67-0.76) were independent factors determining whether patients received amiodarone within the optimal time.

CONCLUSIONS

Earlier amiodarone administration was associated with improved survival. Strategies aimed at reducing delay to amiodarone administration have the potential to improve outcome.